This study will examine risk heterogeneity in age patterns of mortality of cause, at various levels of population. Risk of death from major causes of mortality, by age, will be parametrically described, taking account of competing causes. This will be related to the theory of human aging. Risk-rate parameters will be characterized statistically, including their sampling variances, their geographic and temporal clustering, and their inter-cause correlations. This will first be done using national and international data. Then, county specific mortality will be examined for the state of Texas, providing risk-age assessment for degenerative disease in population groups characterized by ethnicity, geography, and urbanicity. Finally, risk functions will be estimated for the Mexican-Americans of the city of Laredo, Texas. Here, multiple causes of death will be used to refine risk assessments in the presence of competing causes. The risk structure thus determined will be used to detect genetic clustering, or familial risk heterogeneity, in cause and age at death among the extended genealogies of Laredo. Disease frequency projections will be made based on this work.